Electrical controller



March 30 1926. 1,579,018

w. R. MILBURN ELECTRICAL CONTROLLER Filed August 5, 1922 LOWER HMST f I I INVENTOR.

ATTORNEY Patented Mar. 30, 1926.

UNITED STATES PATENT OFFICE.

WILLIAM B. MILBURN, or MILWAUKEE, Wisconsin, ASSIGNOR TO THE cn'rnnn- HAMMER MFG. 00., or MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

ELEcrRioAL CONTROLLER.

Application filed August 5, 1922. Serial No. 579,869.,

To all whom it may concern:

Be it known that I, WILLIAM R. MILBURN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Electrical Controllers, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

This invention relates to electrical controllers and more particularly to manually operable acceleration controllers as for example controllers of the drum type.

An object of the invention is that of pro viding such a controller wherein a portion of the accelerating resistance may be reineluded temporarily in circuit for protection of the controlled motor under predeterminable conditions of overload, as for example upon stalling of the motor.

Another object is that of providing such a controller requiring for exclusionof such resistance when so reincluded, such operation of the drum as to enable subsequent starting of the motor only when protected by a value of accelerating resistance above a predetermined minimum value.

Another object is that of providing an exceedingly simple and reliable controller possessing the foregoing characteristics.

Other objects and advantages will hereinafter appear. 7

The invention is applicable to numerous types of drum controller as exemplified in the accompanying drawing wherein Fig. 1 is a diagrammatic illustration of a drum controller of the full reversing type, embodying the invention, while,'Fig. 2 is a similar view illustrating an adaptation of the invention to a drum controller adapted to provide dynamic lowering. 7

Referring first to Fig. l of the drawing, the same illustrates a reversible motor ineluding armature A and series field F to be supplied from lines L and L and being pro vided with a series brake release winding B and steps of accelerating resistance R to R Certain of said. resistance steps being moreover capable of use for protection of the motor under given conditions of overload as when in stalled condition, the control of the foregoing instrumentalities being effected by means of a controller drum indicated generally at D in association with electro magnetic switches including a resistance switch S and a so-called jamming relay J.

The motor and its directly associated parts including the accelerating resistance, at least so far as involves the ordinary starting functions of the latter, may be of a con ventional type whereas the drum with the exception of the lower three fingers thereof and the segments co-operating therewith may be a standard full reversing drum whereby the aforementioned elements warrant no particular description herein.

The resistanceswitch S is provided with a set of normally open contacts 5 and an additional set 6 ofnormally closed contacts, the switch being biased by gravity or otherwise to effect closure of the contacts 5 but being on the other handconstrained under normal conditions to maintain said contacts open and the contacts 6 closed, due to continuous energization'of its actuating coil 7 under normal conditions. Said switch is further provided with auxiliary maintaining contacts 8. 7 a

The circuit of said actuating coil 7 of the switch S is subjected to control by the jamming relay J, the latter being normally closed and provided with a series opening coil 9 and a shunt holding coil 10 the circuit of the latter including a current limiting resistor 11 whereby said holding coil is protected and rendered incapable of ef-- fecting opening of the switch when closed. The circuit of the actuating coil 7 of switch S is made through the lowermost contact of the drum D, its co-operating segment being proportioned with reference to the third or maintaining contact to insure maintenance of energization of said coil 7 during movement of the drum to its first on positions.

The maintaining circuit of said actuating coil of switch S andalso the circuit of holding coil 10 of relay J are both connected by way of the third drum contact from the bottom, said contact being provided with co-operating segments symmetricallyv arranged to be in engagement therewith for all on positions ofthe drum. The second drum contact from the bottom is connected with line L and is adapted to be at all times in engagement with its associated continuous drum segment to which the aforementioned segments are permanently connectednvhere by all of said segments are at all tunes in connection with line L The operation of the c mtroller may be described as follows, the parts being initially in the relative positions illustrated. In such relation it is obvious that the motor field and armature are disconnected from both supply lines, the switch S being in its up or normal running position and the relay J being closed.

Upon movement of the drum to either of its first on positions circuit is established through the motor armature and field in a relation suitable for rotation of the armature in a corresponding direction, the accelerating resistance being all included in circuit, and the various circuit connections being conventional and obvious as far as the fourth drum contact from the bottom of the drum. The motor circuit extends from this point by conductor 12 through the opening coil 9 of relay J thence by conductor 18 through the normally closed contacts 6 of switch S to line L Progressive movement of the drum through its succeeding positions serves merely to exclude the steps of resistance R to R progressively for acceleration of the motor in the usual manner.

However, if during positioning of the drum in any on position except the first the motor becomes subjected to overload of a value sufficient to cause opening oi 'the relay J through energization of its actuating winding 9 above the predetermined value said relay is adapted to open and remain open under the holding action of coillO, thereby interrupting the energizing cireuit'of coil 7 of the switch S, whereupon said switch is adapted to drop under its bias thereby shiftingthe connection of the motor circuit with line L from that formerly tracedto the following, viz, from line L through the down contacts of said switch S by conductor 14 to a pre-determined intermediate point in the accelerating resistance R to R as for example, the tap between resistance sections R and R the effect being to include in the motor circuit a portion of the accelerating resistance. The value of the accelerating resistance so included will be the total value of the resistance steps located between the motor and such predetermined point, except that in certain positions of the drum a single step of such resistance may be excluded due to'thenecessary overlap of the drum contacts and in determining the location of such predetermined point such possible exclusion of a single step of the resistance is of course to be considered.

The aforedescribed tripping of the switch S serves additionally to interrupt the maintaining circuit thereof through opening of its auxiliary contacts 8 whereby upon sub sequent closure of the relay J the circuit of actuating coil 7 of said switch S is not reestablished autoumtically but on the contrary said switch S reu'iains in its down position pending return of the drum to'off position wherein its lowern'mst contact is in engagement with the (Jo-operating segment thereof, whereas obviously in the latter case the motor circuit. is protected by the total value of the accelerating resistance, and in the former case the motor circuit can be completed only subject to such protection.

Resetting of the device is effected by return of thedrum to off position whereby both coils 9 and 10 of relay J are de-energized thus permitting said relay to close. Such action serves to complete the energizing circuit of coil 7 of switch S, whereupon said switch moves to its upper position. The parts are then in the relative positions illustrated and the aforedescribed cycle of operations may be repeated.

The various control or pilot circuits although obvious may be traced as follows. The holding circuit of relay J extends from line L by conductor through current limiting resistance 11 and through coil 10 thence by conductor 16 to the third drum contact counting from the bottom as aforedescribed. The circuit of the actuating coil 7 of the switch S extends similarly from line L by conductor 15 through relay J thence by conductor 17 through said coil 7 by conductor 18 to the lowermost contact of the drum. The maintaining circuit for said switch S extends from line L through the actuating winding 7 thereof as formerly traced then by conductor 19 through the auxiliary contacts 8 andby conductors 20 and 16 to the third drum Contact as formerly described. I

Considering now Fig. 2 of the drawing it is apparent that the switch S and relay J are precisely similar to the corresponding elements of the construction just described, whereas the functions and circuit connections of said switches are also identical or similar. The motor and its connections, however, have been modified in a conventional manner to adapt the same to effect dynamic lowering of overhauling loads, whereas the structure of the drum has been modified to provide for such dynamic lowering and also to restrict the action of the resistance switch S and the jamming relay J to that portion or" the operative cycle wherein the right hand-or hoist side of the drum is active.

Thus duringthe hoisting portion of the operative cycle the action of the controller is in all respects similar to that just clescribed and hence appears to warrant no further description or explanation herein.

On the other hand during lowering these particular features are inactive having in fact no function to perform, the dynamic lowering provided by the drum being merely a conventional and well known form of such lowering action. T

Here it may be observed that the aforedcscriliied protective devices are aprflicable to numerous forms of drum controller other than those herein illustrated and described, the specific examples herein given being only typical.

Further it is to be noted that the point of connection of conductor 14 to the accelerating resistance is preferably so selected that upon stalling of the motor the current to which the same is subjected while in stalled condition shall not exceed the normal current by much more than 25 percent, although of course this value also is capable of variation and preselection by the means disclosed.

lVhat I claim as new and desire to secure by Letters Patent is:

1. A controller for electric motors comprising regulating resistance for the motor, means for excluding and including said resistance, and means acting independently of the former means for insuring inclusion of a predetermined value of said resistance in circuit with the motor under predetermined conditions before or after completion of said resistance excluding operation and for maintaining said predetermined value of resistance in circuit pending a given subsequent operation of said first'mentioned means.

2. A controller for electric motors com prising regulating resistance for the motor, means for excluding and including portions of said resistance, and means acting inde pendently of the former means for automatically including a predetermined value of said resistance in circuit with the motor under predetermined load conditions before or after completion of said resistance excluding operation and for maintaining said predetermined value of resistance in circuit pending a given reverse operation of said first mentioned means.

3. A controller for electric motors comprising regulating resistance for the motor, a drum controller to commutate said resistance. means adapted to provide a por tion of said resistance in circuit with the motor under predetermined load conditions, and associated means requiring operation of the drum to include at least a given value of said resistance in order to neutralize said former means.

4. The combination with a reversible motor, regulating resistance and a reversing drum controller for commutating said resistance, of a switch providing for inclusion of a regulable value of such resistance in the motor circuit automatically under given load conditions, said drum controller and said switch having associated means providing for interruptioi'i of the resistance controlby said switch but only upon such actuation of the drum as to insure a given value of said resistance in the motor circuit.

5. The combination with a reversible motor, regulating resistance and a reversing drum controller for commutating said. re' sistance, of an electroresponsive switch having an operating winding to be energized under normal conditions for holding said switch in'a given position, said switch being biased to a different position for commutating the motor circuit to include therein a portion of the regulating resistance irrespective of positioning of the drum to 6X- clude such portion, and a relay for inter rupting the energizing circuit of said switch under given load conditions.

6. The combination with a reversible motor, regulating resistance and a reversing drum controller for commutating said resistance, of an electroresponsive switch having an operating winding to be energized under normal. conditions for holding said switch in a given position, said switch being biased to a different position for commutating the motor circuit to include therein a portion of the regulating resistance irrespective of positioning of the drum to exclude such portion, a relay to interrupt the energizing circuit of said switch under given load conditions and means for maintaining said circuit de-energized pending such operation of the drum as to insure at least a given value of resistance in the motor circuit.

7. In adynamic lowering controller for electric motors, the combination with the motor, regulating resistance and a control drum therefor, of a switch biased to effect commutation of the motor circuit to include a portion of the regulating resistance irrespective of positioning of the drum to exclude such portion, an operating coil for said switch to be energized under normal conditions for preponderating such bias, a relay to open and effect de-energization of said operating coil under given load conditions of the motor and a holding coil for maintaining said relay open, said drum having associated means providing for de-energization of said holding coil but only upon movement of the drum out of its first on position toward its full off position.

8. The combination with an electric motor, regulating resistance therefor, a drum controller for commutating said resistance, and a switch adapted to automatically insure inclusion of a predetermined value of said resistance under given load conditions irrespective of the position of said drum controller and for maintaining said predetermined value of resistance in circuit pending reinclnsion of a given amount of resistance in circuit by said drum controller.

9. lhe combination With an electric inotor, regulating resistance therefor, a drum controller for COHlInIltHtlHQ' said resistance, a switch having norn'lally closed contacts in series with all of said resistance and normally open contacts adapted when closed to be in series with a portion of said resistance, and a jamming relay for effecting opening of sald first lnentlonecl contacts and closure of sale! last mentioned contacts under given load conditlons.

In wltness whereof I have hereunto subscribediny name.

WILLIAM R. MILBURN. 

